Untethered, manned and un-manned, EVs are increasingly employed, or considered, for transportation, or other missions, on land, sea, air and extraterrestrial locations. The inability of many EVs to operate in extreme environments and/or for extended, long-endurance, missions is a frequent limitation. As EV usage increasingly overlaps with wider human activity, operational safety also becomes more of a challenge and concern.
Untethered, manned and un-manned, EV operation and safety critically depends on the ready availability of sufficient electrical power for propulsion, operating systems and payloads. Electrical power systems, which support these functions typically include a battery, a means of charging the battery, a means of power distribution and control, to EV sub-systems. The means of charging may be pluggable, or deliverable, external sources and/or in-vehicle generation systems, such as fueled generators, or renewable sources, such as solar Photovoltaic (PV) cell arrays. Pluggable charging may require mission interruption, deliverable sources are vulnerable and fueled options are exhaustible. Solutions which include in-vehicle renewable sources are the only option for uninterrupted, long-endurance, missions.
The performance of EV power systems is critical for operational capabilities and endurance. The performance of power systems, and components, may depend on the operating environment including temperature. For example, PV sub-systems are most efficient at low temperature, while batteries, such as Li-ion batteries, typically deliver optimum performance within a specific range of temperatures, below which they are less efficient and above which they can be prone to catastrophic failure. Operating, or storing, batteries at non-optimal temperatures may also degrade their performance, or accelerate degradation during subsequent use. Self-heating effects during charging and discharging may also cause degradation, if there is insufficient means to dissipate the heat and maintain temperature within an optimum range. A means of thermal energy management, for maintaining preferred operating temperatures in EVs, each subsystem and/or component is therefore desirable.
Thermal energy management in EVs and sub-systems, including power systems, can be critical for the capabilities, performance, endurance and operational lifetime of an EV. Traditional thermal energy management is typically focused on the separate management of individual systems or components. This approach can result in net increases in size, weight, power-consumption, manufacturing complexity and cost of the EV, which can impair the mission capabilities and endurance. More holistic, or integrated, thermal management solutions for EVs and subsystems, which minimize such impairments are desirable. The present invention falls within this domain.
The present invention provides, a holistic, integrated, thermal energy management solution, which can provide advantages in size, weight, power, manufacturing and/or cost of EVs and subsystems, in comparison to traditional energy management approaches. The invention may include “coupled” thermal management of components, with inverse temperature requirements, such as PV cells and batteries, and/or the implementation of multi-functionality within EV structures, or subsystems, such as thermal energy storage within the frame or the battery. Such solutions may be passively, or actively, initiated and may be configured to manage EV performance up to the mission level rather than just the system, or component, levels.
There are EV missions, where it may be advantageous for an EV to have a net absorption, or acquisition, of thermal energy from external, preferably renewable, sources such as sunlight. For example, missions in cold environments, where the environmental temperatures are predominantly below the optimal operational range for the EV, subsystems or components.
There are EV missions, where it may be advantageous for an EV to have a net loss, or dissipation, of thermal energy to the surroundings, by conductive, convective or radiative means. For example, missions in hot environments, where the environmental temperatures are predominantly above the optimal range for the EV, subsystems or components.
There are EV missions, where the environment temperature may vary both below, and above, critical operating temperatures of the EV, subsystems or components. For example, missions which include diurnal conditions or variable locations.
There are EV missions, where it may suffice to alternate between thermal absorption or thermal dissipation operation, in order to thermally manage the EV, subsystems and components.
There are EV missions where it may be advantageous, or necessary, to store thermal energy during some periods of the mission to provide a reserve to offset other periods which have a deficiency.
Thermal energy management systems, will ultimately be dependent on the controllable, or predictable, distribution of thermal energy within the EV, and to, or from, their surrounding environment. The integration of thermal interconnects, backplanes, or conduits, between systems or components in the EV can support such distribution and the addition of means to passively, or selectively, enable, or interrupt, thermal energy transport along these pathways can provide a means of management and control.